Semrush issues this notice when page(s) only have one incoming link and pages that take more than three clicks to be reached.
Generally speaking, the conventional wisdom within SEO community is that you keep your crawl depth under 3 clicks in order to keep it easy for users and search engine bots to easily find your content.
When the notice exists, it is a sign that a site's internal link architecture may be poor. However, this is not always true.
Not having a "home" link in your navigation is probably causing it. Most sites that don't have a "home" link in their primary nav will just hyperlink their logo in the top corner of their header.
If you don't have a logo in the top corner of your header, and don't want to have a "home" link in your primary nav, I would suggest implementing breadcrumbs.
A good UX will provide users a convenient, accessible, and clear way to fully navigate a site.
For more information:
[FIX] Pages need more than 3 clicks to be reached